1. Field of the Invention
The present invention relates generally to a rear wheel hub and drive train assembly for a bicycle and, more particularly, to a rear wheel hub and chainless drive train gear assembly which is operable in conjunction with a spindle, crank arms and pedals to drivingly rotate the rear wheel of a bicycle at either a single speed or at multiple selected speeds.
2. Discussion of the Related Art
The drive train design of most bicycles incorporates a chain connected between a sprocket and a gear assembly near the rear wheel hub. Typically, the sprocket is fitted to an axle extending through a bearing on the bicycle frame between the front and rear wheels. The sprocket, driven directly by pedals attached to crank arms, rotates to move the chain about a loop between the sprocket and the gear assembly. On multi-speed bicycles, having several different gear speeds, a derailer is provided for moving the chain among various sized gears at the gear assembly near the rear wheel hub. Derailers, which are typically operated by a cable and control on the handlebars, have been known to be problematic. On many occasions, the derailer will not successfully move the chain from one gear size to the next, causing the chain to become xe2x80x9cderailedxe2x80x9d in disengagement with the gear assembly. When this happens, the bicycle rider is required to manually place the chain back into engagement with teeth on one of the gears near the rear wheel, and then, upon rotating the pedals, the chain is fully becomes re-engaged with the gears. This process can sometimes by frustrating and messy, causing the bicycle rider""s hands to be covered with grease from the chain. Also, because the chain and gear assembly are openly exposed to the environment, sand, dirt and other debris eventually attach to the grease on the chain and gears, causing excessive grinding and wear of both the chain and gears. This can also interfere with effective engagement of the chain between the various gear sizes when switching between gear speeds. A further problem resulting from the exposed nature of the chain driven drive train assemblies of bicycles is entanglement of clothing, shoelaces, and other articles with the chain and the sprocket gear and/or rear gear assembly.
Chain driven drive gear assemblies present a further problem of adding extra weight to the bicycle. Specifically, the requirement of a sprocket gear, sprocket bearing, and chain add extra weight to the bicycle. Moreover, the positioning of the sprocket and pedals requires significant spacing between the front and rear wheels, thereby requiring a longer frame to separate the front and rear wheels. This also adds to the weight of the bicycle, which is undesirable, particularly, in competitive bicycling sports, such as racing and acrobatics.
In an attempt to improve the gear systems on bicycles, others have proposed various mechanisms and apparatus for increasing the efficiency and longevity of the drive train assembly. In particular, the U.S. patent to Nagano, U. S. Pat. No. 5,273,500, discloses a self-contained change speed apparatus for use on a bicycle. The apparatus in Nagano includes a drive member and a hub body rotatably supported on a fixed shaft, and two planetary gear mechanisms arranged on a drive transmission path extending from the drive member to the hub body. The drive member has a chain wheel or gear which is driven by a drive chain. The drive chain extends to a forwardly positioned sprocket and pedal assembly, of a conventional arrangement. Accordingly, while the Nagano apparatus provides an improvement to the gear arrangement and assembly on the bicycle for changing speeds, the problems associated with a chain driven drive train assembly remain unsolved.
Accordingly, in view of the problems and shortcomings of the various drive train gear assemblies in the bicycle art, there still remains an urgent need for an improved, chainless drive train assembly which is incorporated within the rear wheel hub of a bicycle and in direct, axial driven engagement with the pedals and crank arms of the bicycle.
With the foregoing in mind, it is a primary object of the present invention to provide an improved drive train assembly for use on bicycles which eliminates the use of a chain.
It is also a primary object of the present invention to provide an improved driven train assembly for bicycles which is incorporated within the rear wheel hub and which further includes an axial spindle which is concentric with the rear wheel hub and drive train gear assembly and which is driven directly by crank arms and pedals without the use of a chain.
It is still a further object of the present invention to provide a rear wheel hub and chainless drive train gear assembly which enables closer spacing of the front and rear wheels of a bicycle, thereby reducing weight of the bicycle.
It is still a further object of the present invention to provide a rear wheel hub and chainless drive train gear assembly for a bicycle which is specifically structured and disposed to permit optimal positioning of the bicycle rider relative to the rear wheel of the bicycle.
It is still a further object of the present invention to provide a rear wheel hub and chainless drive train gear assembly which is structured and disposed to permit a bicycle rider to pedal the bicycle while seated at an advantageous posture.
It is still a further object of the present invention to provide a rear wheel hub and drive train gear assembly which is adapted for use in conjunction with a bicycle having an adjustable chest rest and an adjustable handle bar, to enable positioning of the bicycle rider at an optimal posture, thereby reducing wind resistance, muscle fatigue and the likelihood of injury, while increasing the bicycle rider""s output and performance.
These and other objects and advantages of the present invention are more readily apparent with reference to the detailed description and accompanying drawings.
The present invention is directed to a rear wheel hub and drive train gear assembly for use on a bicycle having a hub axle bracket shell fixed to the frame of the bicycle, a spindle extending axially through the hub axle bracket shell and rotatable therein upon application of a pedaling force transmitted through left and right crank arms attached to opposite ends of the spindle. A primary drive gear fitted to the spindle drivingly engages carrier gears which operate a planet gear cage housing and multiple planetary gear and sun gear arrangement according to various gear ratios determined by selectively operation of a clutch assembly. Direct attachment of the pedal operated crank arms to the spindle provides a chainless drive train assembly for rotating the rear bicycle wheel. Planetary gear groups each include an integral set of planetary gears of varying size which mesh with corresponding sun gear rings. Operation of the clutch assembly serves to selectively engagement pawl stops with a corresponding sun gear ring, thereby engaging the corresponding sun gear ring with the planetary gear of the planetary gear groups. The planetary gear groups drive an annular gear ring and an associated annular needle bearing which, in a forward clockwise rotation, engages the hub body to rotate the rear bicycle wheel. Reverse rotation of the annular gear, in a counterclockwise rotation, results in a freewheeling of the drive train gear assembly relative to the hub body.